I ran this command: Add SSL certificate (in NGINX)
It produced this output: See added picture
My web server is (include version): Don't know?
The operating system my web server runs on is (include version): unRAID 6.12.14
I can login to a root shell on my machine (yes or no, or I don't know): Yes
I'm using a control panel to manage my site (no, or provide the name and version of the control panel): unRAID/NGINX
The version of my client is (e.g. output of certbot --version or certbot-auto --version if you're using Certbot):
certbot
Saving debug log to /var/log/letsencrypt/letsencrypt.log
Certbot doesn't know how to automatically configure the web server on this system. However, it can still get a certificate for you. Please run "certbot certonly" to do so. You'll need to manually configure your web server to use the resulting certificate.
certbot certonly
Saving debug log to /var/log/letsencrypt/letsencrypt.log
How would you like to authenticate with the ACME CA?
1: Runs an HTTP server locally which serves the necessary validation files under
the /.well-known/acme-challenge/ request path. Suitable if there is no HTTP
server already running. HTTP challenge only (wildcards not supported).
(standalone)
2: Saves the necessary validation files to a .well-known/acme-challenge/
directory within the nominated webroot path. A separate HTTP server must be
running and serving files from the webroot path. HTTP challenge only (wildcards
not supported). (webroot)
Select the appropriate number [1-2] then [enter] (press 'c' to cancel): 1
An unexpected error occurred:
requests.exceptions.ConnectionError: HTTPSConnectionPool(host='acme-v02.api.letsencrypt.org', port=443): Max retries exceeded with url: /directory (Caused by NameResolutionError("<urllib3.connection.HTTPSConnection object at 0x14607afcac90>: Failed to resolve 'acme-v02.api.letsencrypt.org' ([Errno -3] Temporary failure in name resolution)"))
Your webserver is nginx. Everywhere you've mentioned "nginx" yourself, you probably mean "Nginx Proxy Manager", which is some kind of horrible Node.js thing around nginx. And with "horrible" I mean "very difficult to debug for us on this Community" due to the design/implementation of their certificate handling. (I don't have experience with it personally and I want to keep it that way, just the experience of us volunteers with NPM on this Community and the grey hairs it causes..)
Other than that I don't have any additions next to what Mike already said.